This invention relates in general to vehicular brake systems, and in particular is concerned with a control valve mounted on a hydraulic control unit of an electronically controlled brake system.
Electronically controlled brake systems for vehicles are well known. One type of electronically-controlled brake system includes a hydraulic control unit (HCU) connected in fluid communication between a master cylinder and a plurality of wheel brakes. The HCU includes a housing containing control valves and other components for selectively controlling hydraulic brake pressure at the wheel brakes.
Control valves for HCU""s are commonly formed as electronically actuated solenoid valves. A typical solenoid valve includes a cylindrical armature slidably received in a flux tube or sleeve for movement relative to a valve seat. A spring is used to bias the armature in an open or closed position, thereby permitting or blocking fluid flow through the valve, respectively. A coil subassembly is provided about the flux tube. When the valve is energized, an electromagnetic flux generated by the coil subassembly slides the armature from the biased open or closed position to a closed or open position, respectively.
Control valves mounted on a HCU are actuated by an electronic control module to provide desired braking functions such as anti-lock braking, traction control, and vehicle stability control.
It is desirable that a control valve provides fluid control in a manner proportional to the amount of current applied to the coil subassembly. Such proportional control valves result in enhanced performance of an electronically controlled brake system. Furthermore, it is desirable that a control valve be easily assembled to reduce costs.
This invention relates to a control valve mounted on a hydraulic control unit of a vehicular brake system. The control valve includes a symetrically-formed armature slidably received in a flux tube. The flux tube includes an end cap, a thick tube section, and a thin tube section. The flux tube is pressed into a collar of a valve seat or adapter. The collar and flux tube are sized so that an air gap is provided between a portion of the thin tube section and a coil. The thin tube section and air gap result in the concentration of an electronic flux in the thick tube section and collar. Concentration of the magnetic flux in these areas produces desired magnetic reactions of the control valve. The control valve is economical to manufacture and relatively easy to assembly.
In a preferred embodiment, a control valve for controlling fluid flow in a hydraulic control unit of a vehicular brake system includes a flux tube having an end cap, a thick tube section, and a thin tube section defining an interior volume. An armature is slidably received in the interior volume of the flux tube. A coil is provided about the flux tube. A collar covers a portion of the thin tube section and is spaced from the thick tube section so that an air gap is provided between the coil and the portion of the thin tube section not covered by the collar.
This control valve is particularly adapted to be mounted in a bore of a housing of a hydraulic control unit of an electronically controlled vehicular brake system.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.